/*
 * Copyright (c) 2011-2012 Alexander Dubu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * o  Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * o  Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * o  Neither the name Axil nor the names of its contributors may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
package axil.framework.validation;

import axil.etc.Identity;
import axil.etc.Immutable;

import static axil.framework.Functions.quote;


/**
 * The location (field) in an object where a validation error was detected.
 * These objects form a chain all the way back to the root object where the
 * validation process was started.
 */
public class Location implements Identity, Immutable {
	private static final int undefined = -1;

	private final Location parent;
	private final String member;
	private final String key;
	private final int index;


	public Location(Location parent, String member) {
		this.parent = parent;
		this.member = member;
		this.key = null;
		this.index = undefined;
	}


	public Location(Location parent, String member, String key) {
		this.parent = parent;
		this.member = member;
		this.key = key;
		this.index = undefined;
	}


	public Location(Location parent, String member, int index) {
		this.parent = parent;
		this.member = member;
		this.index = index;
		this.key = null;
	}


	/**
	 * Get the unique identity for this object. The string returned is never
	 * empty and contains no punctuation characters beyond a possible '-'. The
	 * value is suitable for use as an identifier.
	 */
	public String identity() {
		return member;
	}


	public Location rest() {
		return parent;
	}


	/**
	 * Indicates whether some other object is equal to this one.
	 */
	public boolean equals(Object object) {
		if (object != null) {
			if (object instanceof Location) {
				return this.member.equals(((Location)object).member);
			}
		}
		return false;
	}


	private StringBuilder build(StringBuilder text) {
		if (parent != null) {
			parent.build(text);
			text.append(" -> ");
		}
		text.append(toString());
		return text;
	}


	public String path() {
		return build(new StringBuilder()).toString();
	}


	/**
	 * Return a string representation of this object. The string returned is
	 * never null.
	 */
	public String toString() {
		if (key != null) {
			return member + ", item " + quote(key);
		}
		if (index != undefined) {
			return member + ", position " + index;
		}
		return member;
	}
}
